The explicit expression of orbital angular momentum (OAM) spiral spectrum of Laguerre-Gaussian (LG) beam propagating in anisotropic plasma turbulence is derived based on Rytov theory. The relationship between the detection probability of OAM and the crosstalk with the anisotropy parameters, topological charge, radial index, wavelength, beam width, receiving aperture, inner and outer scales are discussed in detail. In order to quantify the effect of plasma turbulence, we compared it with atmospheric turbulence based on restriction function. To optimize OAM detection probability, we also compared the effects of circular aperture method (CAM) with focusing mirror method (FMM) on the propagation characteristics of the spiral spectrum. The results show that even in the strong turbulence region of atmospheric turbulence, the radial dimension of LG beam in plasma turbulence is nearly twice that of atmospheric turbulence and the modes crosstalk has almost reached its upper bound. Besides, by comparing the two optimization methods, we found the ability to reduce crosstalk is related to the choice of beam width and receiving aperture. Therefore, we give a method to optimally select between the CAM and the FMM. We found the corresponding relationship and gave an analytical formula. The FMM has a greater ability to reduce crosstalk than the CAM when the beam width ≥4 cm and the aperture ≥3 cm. We quantified the effect of plasma turbulence and provide a guideline for the selection of beam width and receiving aperture under these two optimization methods. The research results may be helpful in the field of optical communication.

中文翻译：

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拉盖尔高斯光束在各向异性湍流等离子体中传播的螺旋谱


基于Rytov理论，推导了各向异性等离子体湍流中拉盖尔-高斯(LG)光束的轨道角动量(OAM)螺旋谱的显式表达式。详细讨论了OAM的检测概率和串扰与各向异性参数、拓扑电荷、径向指数、波长、波束宽度、接收孔径、内外尺度的关系。为了量化等离子体湍流的影响，我们将其与基于限制函数的大气湍流进行比较。为了优化OAM检测概率，我们还比较了圆孔径法（CAM）和聚焦镜法（FMM）对螺旋光谱传播特性的影响。结果表明，即使在大气湍流的强湍流区域，等离子体湍流中LG光束的径向尺寸也接近大气湍流的两倍，模态串扰也几乎达到其上限。另外，通过比较两种优化方法，我们发现降低串扰的能力与波束宽度和接收孔径的选择有关。因此，我们给出了一种在 CAM 和 FMM 之间进行最佳选择的方法。我们找到了对应关系并给出了解析公式。当波束宽度≥4 cm且孔径≥3 cm时，FMM比CAM具有更强的降低串扰的能力。我们量化了等离子体湍流的影响，并为这两种优化方法下波束宽度和接收孔径的选择提供了指导。该研究成果可能对光通信领域有所帮助。